Carson joins the fray.

Five things you should know about the fourth entrant in the GOP race for President.

According to the latest polls, most Americans know very little about Dr. Ben Carson, a Florida neurosurgeon who is the first non-politician to officially enter the 2016 race for President. But there is no doubt that Carson has developed a fervent grassroots following among conservative Republicans. As he launches his presidential campaign, here are five things things you should know about Ben Carson.